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How can I check in my .bashrc if an alias was already set.
When I source a .bashrc file, which has a function name, say fun, and my current environment has an alias as fun also.
I tried unalias fun, but that will give me an error that fun not found when my environment wont have that alias already.
So in my .bashrc, in my fun function I want to check if alias was set, then unalias that.
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How to list existing Bash Alias? You can use the alias -p command to list all the alias currently defined. that contains the list of aliases as created by the Bash alias builtin. $BASH_ALIASES will lose its special properties when being unset.
We use the compgen -a command to list all the available aliases: $ compgen -a alert egrep fgrep grep l la ll ls ... Here, the -a option tells compgen to list all the aliases.
To view the alias for a particular name, enter the command alias followed by the name of the alias. Most Linux distributions define at least some aliases. Enter an alias command to see which aliases are in effect. You can delete the aliases you do not want from the appropriate startup file.
If you just want to make sure that the alias doesn't exist, just unalias it and redirect its error to /dev/null like this:
unalias foo 2>/dev/null You can check if an alias is set with something like this:
alias foo >/dev/null 2>&1 && echo "foo is set as an alias" || echo "foo is not an alias" As stated in the manpage:
For each name in the argument list for which no value is sup- plied, the name and value of the alias is printed. Alias returns true unless a name is given for which no alias has been defined. Just use the command alias like
alias | grep my_previous_alias Note that you can actually use unalias, so you could do something like
[ `alias | grep my_previous_alias | wc -l` != 0 ] && unalias my_previous_alias That will remove the alias if it was set.
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